CIE A Level Chemistry
CIE A Level Chemistry Nitrogen and Sulfur Exam Questions
Free CIE A Level Chemistry exam questions for Nitrogen and Sulfur, with a mark scheme for every pack. Covers unreactivity of nitrogen, ammonia and the ammonium ion, nitrogen oxides from engines, catalytic converters, sulfur dioxide and acid rain.
Nitrogen and Sulfur exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
StemUp mark scheme flashcards
A-Level Chemistry Flashcards for 2027 Onwards
Every answer is written in mark scheme wording, so you learn exactly what examiners give marks for. Then test yourself with the questions on this page.
From £10.99View flashcards
About CIE A Level Chemistry Nitrogen and Sulfur
Nitrogen and sulfur in Cambridge International 9701 is a short AS topic with a strong environmental focus. You need to explain why nitrogen gas is unreactive, describe ammonia as a Bronsted-Lowry base and the shape and formation of the ammonium ion, and know how ammonia is displaced from ammonium salts. The topic covers the formation of nitrogen oxides in car engines and lightning, their removal using catalytic converters, and the role of nitrogen oxides in photochemical smog and in catalysing the oxidation of sulfur dioxide. Sulfur dioxide formation and its role in acid rain complete the topic. It links to bonding, equilibria and Group 2, and examiners favour short equations.
What you need to know
- Unreactivity of nitrogen N2 has a strong triple bond (bond energy about 944 kJ mol-1) and is non-polar, so it has little tendency to react under normal conditions.
- Ammonia and ammonium Ammonia accepts a proton using its lone pair to form NH4+, which is tetrahedral with bond angles of 109.5. The ammonium ion contains a coordinate bond.
- Displacement of ammonia Warming an ammonium salt with a base releases ammonia, for example NH4Cl + NaOH → NaCl + NH3 + H2O. Ammonia turns damp red litmus blue.
- Nitrogen oxides At the high temperatures in engines and lightning, N2 and O2 combine to form NO, which is oxidised to NO2. NO and NO2 contribute to photochemical smog and acid rain.
- Catalytic converters Platinum or rhodium catalysts remove NO and CO, for example 2CO + 2NO → 2CO2 + N2.
- Sulfur dioxide and acid rain SO2 forms when fuels containing sulfur are burned. NO2 catalyses its oxidation: SO2 + NO2 → SO3 + NO, then NO + 1/2O2 → NO2, and SO3 dissolves in water to form sulfuric acid in acid rain.
Common mistakes in Nitrogen and Sulfur
- Explaining nitrogen's unreactivity only by saying it is a gas; the key reason is the high bond energy of the N≡N triple bond.
- Forgetting that NO2 is regenerated in the oxidation of SO2, so it acts as a catalyst.
- Saying ammonia has a tetrahedral shape; NH3 is pyramidal, it is NH4+ that is tetrahedral.
- Writing that catalytic converters remove carbon dioxide; they convert CO and NO into CO2 and N2.
- Saying NO is formed from nitrogen in the fuel; it forms mainly from atmospheric N2 and O2 at high temperature.
Try three Nitrogen and Sulfur exam-style questions
1. Explain why nitrogen gas is unreactive. (2 marks)
Show the mark scheme answer
Strong N≡N triple bond with high bond energy; molecule is non-polar so it does not attract electrophiles or nucleophiles.
2. Write equations to show how nitrogen dioxide acts as a catalyst in the oxidation of atmospheric sulfur dioxide. (2 marks)
Show the mark scheme answer
SO2 + NO2 → SO3 + NO; NO + 1/2O2 → NO2.
3. Describe and explain how ammonia can be produced from ammonium chloride in the laboratory. (2 marks)
Show the mark scheme answer
Warm ammonium chloride with a base such as calcium hydroxide or sodium hydroxide; the stronger base (OH-) removes a proton from NH4+, releasing NH3 gas.
Nitrogen and Sulfur FAQs
What does Cambridge AS & A Level Chemistry Nitrogen and sulfur cover?
It covers the unreactivity of nitrogen, ammonia and ammonium salts, nitrogen oxides and catalytic converters, and sulfur dioxide and acid rain.
How do I revise Nitrogen and sulfur?
Learn the short list of equations, practise explaining each environmental problem in two or three steps, and link ammonia to Bronsted-Lowry theory and bonding.
Which equations do I need?
N2 + O2 → 2NO, 2NO + O2 → 2NO2, 2CO + 2NO → 2CO2 + N2, the NO2 catalytic cycle for SO2, NH3 + H+ → NH4+ and the displacement of ammonia from ammonium salts.
